1. Field of the Invention
The present invention relates to a technology for storing videos.
2. Description of Related Art
Recently, a format for storing video content, such as security camera footage and live video, has changed to a digital format which does not have the image degradation of an analog format. With the shift to digital format, there is increased interest in technology for storing video in a system connected to a network. Requirements and needs for video storage technology vary form small-scale video storage technology for room monitoring and the like, to large-scale video storage technology for wide area monitoring, such monitoring a city, or monitoring river traffic
A video storage method which receives and stores video data sent from multiple cameras (e.g., security cameras) is known. In conventional technology each of the cameras sends a store-request, i.e., control data, to the video storage unit and sends video data in response to a reply from video storage. Because the quantity of video simultaneously stored in video storage is limited, however, depending in video storage performance, a load balancer (load distribution device) which distributes video data to a number of video storage units is used to handle an increased number of cameras.
In general, the load balancer and the video storage are installed in a monitoring center or the like, and the cameras are distributed widely over the whole monitoring area. Since it is necessary to protect the video storage in a monitoring system designed for crime prevention, a protection device called a firewall is also used. Installing a firewall device in the monitoring center protects the load balancer and video storage from unauthorized access aimed at obstructing monitoring. In the conventional load balancing technology using a Domain Name System (DNS) round-robin function, a plurality of unique IP addresses corresponding to a domain name are registered at a DNS server, and every time a query for an IP address is made to the DNS server one of the IP addresses is sent in response to the query. Thus, the accesses made to one domain are distributed to different destinations. More specifically, the DNS server functions as the load balancer, and the IP addresses provided by the DNS server are the addresses of the allocated video storage units. Moreover, a method of selecting a video storage more sophisticated than the DNS round robin design uses information such as an available memory is known.
The firewall is conventional protection technology, i.e. a device protecting a network from unauthorized access from external networks. The various modes of protection use range from the basic process of permitting accesses from the protected network to be protected outside the network and prohibiting outside access to the protected network, to the complicated process of encrypting a packet and investigating the header content. Since a large quantity of data is sent and received for storing video, a high throughput is required of the firewall. Therefore, the complicated security mode requires a high-speed processor, increasing the cost of the firewall.
The PULL access mode is a method for constructing a firewall with high security and high throughput at a low cost. The PULL access mode, blocks external access to everything inside the, and external data are obtained as a reply to an access from inside the firewall to an outside IP address using a known protocol such as HTTP. The PULL access mode is a generally known method of delineating the firewall.
To send external data directly through the firewall, the PUSH access mode is used. To realize the PUSH access mode, a hole for is needed to pass only specific PUSH accesses through the firewall. To prevent the hole from being a security hazard, countermeasures such as timed opening of the hole, usually in combination with an authentication function are required. That is, the PUSH access mode results in increased cost due to the security maintenance compared to using the PULL access mode only.